Groom-to-be Justin Timberlakewas photographed arriving with pals in Cabo San Lucas, Mexico on Friday Sept. 21 -- just a few hours after the festivities wrapped up in Las Vegas, where the singer-actor kicked off a multi-day bachelor party bonanza.

Indeed, a source tells Us Weekly that Timberlake and his posse will be in Cabo for a week to celebrate his impending nuptials to Jessica Biel.

Together for five years, Timberlake, 31, proposed to the "Total Recall" actress, 30, in Jackson, Wyoming, in late December, as first revealed by Us Weekly.

For Thursday's Vegas festivities, Timberlake and his posse wore fedoras and bow-ties, hitting the nightclubs Tryst (at the Wynn Las Vegas) and Surrender (at Encore), and dined at Sinatra Restaurant (at the Wynn). At outdoor pool venue Surrender, Timberlake "was a good boy," says an eyewitness, who points out that the site was packed with models. "It was just him and his guys in their cabana."

Although Biel and Timberlake are expected to wed this year, the duo have been completely tight-lipped about the bash, with sources mentioning such wide-ranging rumored wedding locales as California, Italy and Wyoming.

Currently starring in The Trouble with the Curve, Timberlake told Jay Leno earlier this week that his wife-to-be Biel is a "really good" cook.